The present invention relates to hair cutting and trimming devices in which a length of hair is suctioned into a hollow body and cut therein. More particularly, the present invention relates to improvements in such devices which provide greater versatility, simpler hair length selection, and more convenience in use than is permitted by prior art devices.
It is known in the prior art to use a vacuum source in conjunction with an automatic hair cutting and trimming device. Such prior art may be readily separated into two categories: those in which the vacuum is used only to remove hair clippings from the cutter (as typified by U.S. Pat. Nos. 1,618,713; 2,653,380; and 2,748,472); and those in which the vacuum is also used to stretch out the hair so that it may be cut to a particular length (as typified by U.S. Pat. Nos. 1,238,061; 1,331,218; 1,735,766; 3,654,699; and 3,979,825). The present invention is concerned with the second type of device wherein the vacuum source serves the combined function of removing the clippings and extending the hair. Such devices in the prior art have the clipper located entirely inside the suction path, a feature which makes for many practical disadvantages. For example, the portion of the suction device which is placed against the scalp must be relatively long to accommodate the cutter and therefore requires the user's arms to be held in uncomfortable positions. Further, with the cutter mounted inside the suction device it becomes difficult, if not impossible, to use the cutter independently of the suction device.
It is also important in devices of this type to include gauging means for selectively changing the length of hair to be cut. Such gauging means in the prior art have taken forms such as: a sleeve which threadedly engages the forward end of the device (as in U.S. Pat. No. 1,238,061); a sleeve which slidably engages the forward end of the device (as in U.S. Pat. No. 3,654,699); and means for moving the clipper itself within the body of the device (U.S. Pat. No. 3,979,825). All of these gauging approaches provide for continuous adjustment mechanisms (as opposed to discrete length settings) and are complex to operate and expensive to mass produce.
It is an object of the present invention to provide a hair cutting device which permits hair to be cut to a preselected length by an unskilled person.
It is a further object of this invention to provide for the use of a vacuum means to pull individual hairs into straight line configurations along the length of a gauge which sets the cutting length without requiring the entire clipper set to be inside the walls of the air passage.
It is still a further object of the invention to provide a simple means to change hair cutting length over a wide range without complicating the design and manufacture of the device.
It is a still further object of the invention to provide a hair cutting and gauging device which is neither awkward nor inconvenient for the user to hold and operate.